Field of the Invention
The present invention relates generally to access systems and wheelchair lift arrangements, for example wheelchair lift arrangements for use in connection with a vehicle, and, in particular, to a method of and arrangement for installing a wheelchair lift arrangement in a vehicle, such as a dual parallel-arm, platform-type wheelchair lift arrangement.
Description of Related Art
As is known in the art, access systems and wheelchair lift arrangements are provided to permit access, entry, exit, ingress, egress, and the like from a variety of structures and environments. For example, many vehicles are fitted or configured to interact with a wheelchair lift arrangement to allow a wheelchair (or other limited mobility) user to enter and exit the vehicle. One known type of wheelchair lift arrangement is in the form of a dual parallel-arm, platform-type wheelchair lift.
Since their introduction in the early 1980s, most dual parallel-arm, platform-type wheelchair lifts have been installed in vehicles using a series of bolts and supporting hardware to firmly attach the lift's base plate directly to the vehicle floor structure. Though the relative proximity of the bolts used to attach the lift to the vehicle has made for a spatially-efficient installation, it has also necessarily meant that the load in each fastener is relatively high. As can be seen in FIG. 1, the reactions at locations A and B at the base plate and/or mounting brackets (which are attached to the floor of the vehicle) are on the order of 3 to 4 times the magnitude of the load on the platform of the wheelchair lift arrangement.
As the types of vehicles in which wheelchair (or access) lifts are typically installed have become lighter, the vehicular structure available to which the wheelchair lift arrangement can be anchored has also become lighter, necessitating the use of supplemental reinforcement. As seen in FIG. 2, this supplemental reinforcement may include a sub-frame member configured for engagement with a clamping bar positioned underneath the vehicle floor. One or more of these sub-frame members can be used to support the clamping bar and provide structural reinforcement. However, as expected, the use of supplemental reinforcement leads to a variety of drawbacks and deficiencies, including, but not limited to, (1) additional material and/or installation costs; (2) additional weight, which leads to (i) greater fuel consumption; (ii) additional load on the vehicle's braking system; and (iii) less available payload; and (3) additional structural components, which means more material and labor are required to effect the installation. Further, with the aging of the population, the need for cost-effective care solutions has increased and will continue to increase.
Existing systems may include brackets that attach to the vehicle wall or door frame. However, such systems and arrangements are redundant since the wheelchair lift arrangement must still be bolted to the vehicle floor. Also, such systems and arrangements may lower the load at the attachment point, but the need for more efficient load distribution is required, especially for lighter vehicles (which is the current industry trend).